Birth.Movies.Death and Latino-Review both claim Freeman will appear in the Black Panther movie as well. Furthermore, Latino-Review claims Freeman might play an interrogator of sorts.

The site speculates that this character could very well be Everett K. Ross, a U.S. State Department official and expert on all matters related to Wakanda. In the comics, Ross served as an envoy to the Wakandan king T'Challa.

Everett Ross in the Black Panther comic.

A character such as Ross could easily appear in both Civil War -- which will introduce Chadwick Boseman's Black Panther -- and Black Panther.

Again, this is just a rumor so let's treat it as such until something more official comes along. Still, Everett Ross certainly seems right for Freeman.